(1) Field of the Invention
The present invention relates generally to cargo restraint devices and more particularly to cargo restraint devices using a pawl and ratchet tensioning systems with a belt or strap to secure the cargo to a pallet.
(2) Description of the Related Art
A wide array of cargos are transported each day upon pallets which require restraint devices to securely hold them upon the transport vehicle during transit. Cargo restraint devices typically utilize pawl and ratchet locking mechanisms to keep a strap tight over the cargo. The cargo loaded pallets are stacked on top of one another upon the vehicle, so that the weight of the cargo causes the restraint straps of the lower pallets to loosen and the pawl and ratchet to lock the strap in a more retracted position than originally set by the operator. When the weight of the cargo pallets stacked above are removed at the destination, the straps become exceedingly tight, which wedges the pawl against the teeth of the ratchet under such a pressure so as to make it difficult to disengage the pawl and release the strap. This forces operators to use their hands to release heavy cargos in an unsafe manner. While related cargo restraint devices utilize straps locked by pawl and ratchet systems, there are no hands-free devices which can be easily kicked to force a pawl to disengage from a ratchet to allow a safe and quick release of restraint straps from cargo on a pallet.
U.S. Pat. No. 2,775,463 to Chenette discloses an appliance hand truck having an endless belt track for easy transport up a stairway. The appliance hand truck has a tensioning means for a restraining strap to hold the appliance securely on the truck. The strap tensioning means uses a pawl to prevent the reverse rotation of the ratchet wheel when a strap is under tension. To release the tensions upon the strap, the pawl 44 is disengaged from the ratchet wheel by pulling an end of the pawl to disengage it from the ratchet wheel.
U.S. Pat. No. 3,175,806 to Prete, Jr discloses a ratchet type buckle for tensioning an elongated flexible member such as a strap, rope or cable. The ratchet type buckle has a driving pawl for engaging ratchet teeth. The inner end of the driving pawl is formed with two pawl fingers that straddle the spool for the purpose of engaging the ratchet teeth to drive the spool in the direction to wind in the strap. When the spool is to be released for reverse rotation to release the strap, the handle 64 manually retracts the driving pawl and the pawl is held in the retracted position to prevent further engagement with the ratchet teeth.
U.S. Pat. No. 3,804,368 to Bailey discloses a ratchet tensioner comprising a reciprocal lever mounting a first pawl engaging a ratchet wheel connected to two parallel bars forming a reel. When the lever moves in the opposite direction, the first pawl rides over the ratchet wheel and a second pawl engages the ratchet wheel to prevent unwinding of webbing from the reel. The pawls are lifted out of engagement with the ratchet wheel to allow the reel to freely rotate by manually pulling the release member 37.
U.S. Pat. No. 5,101,537 to Cummings discloses a ratchet tie down structure that is designed to hold heavy objects in place on a transport vehicle. The mechanism includes a base element attached to the transport vehicle that has pair of cooperating elements having interfitting ratchet teeth and a latch that permits a shaft to be turned in one direction to tighten a flexible holding element attached to the object. The ratchet teeth can be disengaged by fitting the plain end of a bar into one of the sockets of the latch and pushing the latch inwardly against the bias of the spring to disengage the ratchet teeth of the two elements.
U.S. Pat. Nos. 5,145,299 and 5,186,586 to Stephenson, Jr. disclose a remote release mechanism which permits restraints such as flat straps placed around a load and placed in tension by a winch to be released by an operator positioned on the same side of the transportation structure as the winch. This permits the hook end of a load restraint to be released from the winch side of the transportation structure, eliminating the need to perform separate operations on either side of the restraint mechanism. The apparatus comprises a hook bar connected to a rotatable drum which is held from rotation in one direction by a pawl 112 and ratchet. The pawl is released by the pulling a remote release rod to swing the pawl from the teeth of the ratchet.
U.S. Pat. No. 5,490,749 to Arbues discloses a winch for securing the tie down straps used to restrain cargo transported on a flatbed vehicle. The winch includes a rigid frame having a rotatable winch drum on which the strap may be wound. A ratchet wheel on the end of the winch drum includes two sets of teeth which are axially offset and circumferentially staggered relative to each other. A pawl for locking the ratchet wheel has two similarly offset and staggered sets of teeth. The teeth of the pawl and ratchet wheel interlock at locations that are both axially and circumferentially offset to distribute the stresses and enhance the structural strength of the winch. The end of the pawl presents a tip 54 which may be gripped with the fingers to release the pawl from the ratchet teeth.
U.S. Pat. No. 5,549,429 to Sergent discloses a tool 30 for manipulating a ratcheted strap-tightening mechanism such as those associated with cargo securing harnesses. The tool comprises a handle having at a first end a socket adapted to engage the lever of the ratcheting mechanism, and a tongue adapted to unlock the ratcheting mechanism at the other end. The tongue is shaped and dimensioned to be inserted between the locking pawl and the drum to pry the pawl away from the teeth of the ratcheting mechanism.
U.S. Pat. No. 5,943,742 to Huang discloses a strap tightening/loosening device having two side plates with a connecting plate, a handle mounted to the side plates with a shaft extending through the handle and the side plates, and two ratchets mounted to the shaft. Each of the two side plates have two slots and an elongated slot, two members slide and are received within the two slots so that one of the members is engaged with the ratchets. The first member has two first pawls which engage the ratchets, while a second member also has two second pawls. The pawls are lifted from the ratchet by cam means when the handle is extended.
U.S. Pat. No. 6,059,499 to Bird discloses a retractable cargo securement strap assembly. A threaded post and a pair of clamps allow for removably mounting the housing of the strap assembly to a vehicle. A spool assembly situated within the housing makes it possible to retract the strap within the housing. The strap assembly has a locking assembly comprising a pivoting pawl which engages the teeth of a ratchet wheel. The pawl is disengaged from the ratchet wheel teeth by pushing a push button lever lifts an elongated arm which lifts the pawl from the teeth of the ratchet wheel.
U.S. Pat. No. 6,141,840 to Berkes discloses a buckle for releasably engaging a tongue of a cargo restraint system. The tongue is released from the buckle by lifting a lever to disengage the tongue. Berkes does not disclose a pawl and ratchet locking system with a lock release for the cargo restraint system.
U.S. Patent Application Publication No. 2003/0031524 to Brunet discloses a strap winch device assembly for fitting on a flat bed open truck trailer, to enable a truck driver to remotely activate the system without leaving the truck cab. The winch devices are connected along the side of the trailer to a single fore and aft drive shaft driven by a motor to tighten any straps that loosen during transit. A cable is connected at one end to a slider plate adjacent to biasing springs and at the other end to a clutch release handle member. Pulling upon the handle member pulls the cable, which moves the slider plate against the coil springs. The pulling force of the cable moves the shaft away from the drive shaft so that the teeth of the gears no longer are intermeshed.
U.S. Patent Application Publication No. 2003/0084550 to Fang discloses a strip safe-releasing device using a pawl and ratchet. A pawl engages the teeth of the ratchet to maintain the tension on the strip. The strip tension can be released by extending the handle so that the convex portion of the handle lifts the pawl from the teeth of the ratchet.
While the related art teach cargo restraint devices, there still exists a need for improved cargo restraints which have simple release mechanisms that do not require use of the hands.